EP3249770B1

EP3249770B1 - Systems and methods for adjusting operations of a gas turbine following a transient event

Info

Publication number: EP3249770B1
Application number: EP17290070.6A
Authority: EP
Inventors: Sreedhar Desabhatla; Alexis Sesmat; Maxime BUQUET; Scott William Szepek
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2016-05-24
Filing date: 2017-05-24
Publication date: 2022-08-10
Anticipated expiration: 2037-05-24
Also published as: EP3249770A1; US10205414B2; US20170346430A1; PL3249770T3

Description

BACKGROUND

The subject matter disclosed herein relates to control of a power generation system following a transient grid event. More specifically, the present disclosure relates to adjusting an operation of a gas turbine following the detection of a transient event on an electrical grid connected to the turbine.
A power generation system includes a prime mover that generates electrical power from other primary energy sources. An exemplary prime mover, a gas turbine, is a rotary mechanical device with a gas turbine shaft that drives an electrical generator to supply electrical power to a transmission grid. The transmission grid, in turn, supplies electricity to various power consumers. To ensure that the power generation system operates effectively, the turbine shaft speed and resulting grid frequency should be synchronized with each other within operational ranges. As such, when grid frequency changes abruptly due to a transient event, improved systems and methods for adjusting the turbine shaft speed in view of the transient even are desired.
US 2015/377057 A1 describes a system and method for controlling a power generation system, which includes a gas turbine and a generator connected to a grid, following a transient grid event. The method includes sensing a rate of change of electrical frequency at terminals of the generator, determining a rate of change of shaft line acceleration, and identifying a transient grid event if the rate of change of shaft line acceleration exceeds a first threshold and the rate of change of electrical frequency at the generator terminals exceeds a second threshold for a specified duration. Once a transient grid event is identified, one or more actions are triggered by a turbine controller to recover from the transient grid event. The turbine controller may preposition the gas turbine to avoid trips or other major events such as a compressor surge by prepositioning the fuel system, or prepositioning inlet guide vanes, or combustion chamber.
US 2014/260293 A1 describes a control system for controlling operation of a gas turbine system. The control system includes a droop response system configured to detect one or more operational characteristics of the gas turbine system as an indication of a frequency variation of a power grid associated with the gas turbine system. The droop response system is further configured to generate a response to vary an output of the gas turbine system in response to the indication of the frequency variation. The controller includes a multivariable droop response correction system configured to generate a plurality of correction factors to apply to the response generated by the droop response system. The plurality of correction factors is configured to adjust normal fuel flow commands, such that for a given variation in frequency of the power grid, the droop power response may be irrespective of the ambient operating conditions, e.g., compressor inlet temperature and pressure, turbine temperature, etc., and the load level of the gas turbine system.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimed embodiments are summarized below. These embodiments are not intended to limit the scope of the claimed embodiments, but rather these embodiments are intended only to provide a brief summary of possible forms of the embodiments described herein. Indeed, the embodiments described within the claims may encompass a variety of forms that may be similar to or different from the embodiments set forth below.
In one embodiment, a system includes a turbine having a first controller configured to control one or more operations of the turbine. The system also includes a generator that couples to the turbine, such that the generator may provide power to an electrical grid. The system also includes an exciter that may provide a direct current (DC) voltage and a DC current to a rotor of the generator. The exciter also includes a second controller that is communicatively connected to the first controller via a communication network and is configured to monitor a first set of electrical properties associated with the electrical grid, determine whether a transient event is present on the electrical grid based on the first set of electrical properties, determine a mechanical power present on a shaft of the generator based on a second set of electrical properties associated with the generator, the electrical grid, or both in response to the transient event being present, wherein the second set of electrical properties comprises an inertia on the shaft in the generator, an accelerating power associated with a rotor of the turbine, and a power output by the generator, and wherein the mechanical power comprises an indication of energy used to rotate the shaft, and send the mechanical power to the first controller via the communication network. The first controller is configured to use the determined mechanical power received from the second controller to update a model based control program to be executed to control operations of the turbine and to adjust the one or more operations of the turbine to provide stability between the first set of electrical properties of the grid in view of the transient event and the rotation of the shaft, based on the received mechanical power.
In another embodiment, a method for use in a system is disclosed, wherein the system includes a turbine comprising a first controller configured to control one or more operations of the turbine, a generator configured to couple to the turbine, wherein the generator is configured to provide power to an electrical grid, and an exciter configured to provide a direct current voltage and a DC current to a rotor of the generator, wherein the exciter comprises a second controller which is communicatively connected to the first controller via a communication network. The method involves monitoring, by the second controller, a first set of electrical properties associated with the electrical grid and determining, by the second controller, whether a transient event is present on the electrical grid based on the first set of electrical properties. The method also involves determining, by the second controller, a mechanical power present on a shaft of the generator based on a second set of electrical properties associated with the generator, the electrical grid, or both in response to the transient event being present, wherein the second set of electrical properties comprises an inertia on the shaft in the generator, an accelerating power associated with a rotor of the turbine, and a power output by the generator, and wherein the mechanical power comprises an indication of energy used to rotate the shaft, and sending the mechanical power from the second controller to the first controller via the communication network, wherein the first controller uses the mechanical power received from the second controller to update a model based control program which is executed to control operations of the turbine and adjusts one or more operations of the turbine to provide stability between the first set of electrical properties of the grid in view of the transient event and the rotation of the shaft, based on the received mechanical power.
In yet another embodiment, a non-transitory computer readable medium may include computer-executable instructions that may cause a processor to perform the method as mentioned before.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present embodiments described herein will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 illustrates a block diagram of a turbine-generator system, in accordance with an embodiment;
FIG. 2 illustrates a flow chart of a method for sending a calculated mechanical power of a shaft during a transient event to a turbine, in accordance with an embodiment;
FIG. 3 illustrates a process flow for calculating a mechanical power of a shaft during a transient event, in accordance with an embodiment; and
FIG. 4 illustrates a flow chart of a method for adjusting operations of a turbine during a transient event, in accordance with an embodiment.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present disclosure, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. One or more specific embodiments of the present embodiments described herein will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
A power generation system may include a turbine and a generator. The turbine may have a prime mover (e.g., turbine shaft) that may provide mechanical energy to the generator, which may then output a voltage or electric potential to a grid. The turbine may include a turbine controller that may adjust a speed at which the turbine shaft may rotate. In one embodiment, the turbine controller may receive an indication that a transient event has occurred on the grid. The transient event may cause the frequency of the voltage output by the generator to deviate from its rated frequency. As such, when a transient event occurs, the generator may adjust its power output to synchronize with the frequency of the grid. However, when the turbine controller attempts to react to the same transient event, the turbine controller may not be able to adjust the speed of the turbine shaft within the same amount of time that the generator synchronizes its output with the grid. This mismatch of the speed of the turbine shaft and the frequency output of the generator may potentially affect the dynamic behavior of the turbine itself.
That is, as the frequency decreases, the speed at which the turbine shaft rotates also decreases. For example, when a frequency drop in the grid occurs, a drop in speed in which the turbine shaft rotates also accors because the speed is directly proportional with the grid frequency. In this case, the fuel intake of the turbine would increase based on sensing the drop in speed, which increases active power output to compensate for the drop in frequency. This increase of fuel intake may or may not match the required change in electrical power over some period of time. As a result, the speed in which the turbine shaft rotates may decrease and eventually result in a trip. Consequently, the turbine controller may shut off fuel to the turbine (e.g., flame out).
To provide enough time for prime mover to react, an exciter controller that controls the operation of the generator detects or recognizes the transient grid event at the initial stages of grid transient to its occurrence. Upon detecting the transient event, the exciter controller sends commands to the turbine controller to adjust the operation of the prime mover and compensate for the change in frequency of the generator. That is, the exciter controller monitors electrical parameters, such as the power output and electrical frequency, of the generator and detects a transient event based on the electrical parameters. While a gas turbine is specifically discussed for explanatory purposes, the embodiments described herein apply to any prime mover and are not limited based on the exemplary system. Additional details regarding adjusting a load set point for a generator are provided below with reference to FIGS. 1-3.
By way of introduction, FIG. 1 illustrates a block diagram of a turbine-generator system 10. As shown in FIG. 1, the turbine-generator system 10 includes a turbine 12, a generator 14, a switch 16, a switch 18, a starter component 20, an exciter component 22, and an electrical grid 24. The turbine 12 may include any one or more turbines and may be configured as a simple cycle or a combined cycle. By way of example, the turbine 12 may include a gas turbine, a wind turbine, a steam turbine, a water turbine, or any combination thereof. In the turbine-generator system 10, the mechanical work output by the turbine 12 may rotate a shaft of the generator 14. In general, the generator 14 may then convert the rotation of the shaft into electrical energy that may be output to the electrical grid 24.
The starter component 20 may be a variable frequency drive, a load commutated inverter (LCI), or a similar type of electrical device that may output an alternating current (AC) voltage that may be provided to a stator of the generator 14. In one embodiment, the starter component 20 may receive an AC voltage from an AC voltage source 32 and may convert the AC voltage into the controlled AC voltage, which may be provided to the stator of the generator via the switch 18.
The exciter component 22 may include an electrical circuit that provides direct current (DC) current and a DC voltage to field windings of a rotor of the generator 14, thereby inducing a magnetic field within the generator 14. The magnetic field may then cause the rotor to spin inside the generator and rotate the shaft of the generator 14. In addition to creating the magnetic field within the generator 14, the exciter component 22 may be used to control the frequency, amplitude, and phase properties of the voltage output by the generator 14. As such, the exciter component 22 may be used to synchronize the voltage output by the generator 14 with the voltage of the electrical grid 24 after the generator's shaft rotates at its rated speed.
The turbine 12, the starter component 20, and the exciter component 22 include a turbine controller 26, a starter controller 28, and an exciter controller 30, which are used to control the turbine 12, the starter component 20, and the exciter component 22, respectively. The turbine controller 26, the starter controller 28, and the exciter controller 30 may each include a communication component, a processor, a memory, a storage, input/output (I/O) ports, and the like. The communication component may be a wireless or wired communication component that may facilitate communication between each component in the turbine-generator system 10, various sensors disposed about the turbine-generator system 10, and the like. The processor may be any type of computer processor or microprocessor capable of executing computer-executable code. The memory and the storage may be any suitable articles of manufacture that can serve as media to store processor-executable code, data, or the like. These articles of manufacture may represent non-transitory computer-readable media (i.e., any suitable form of memory or storage) that may store the processor-executable code used by the processor to, among other things, perform operations that may be used to control the turbine 12, the starter component 20, and the exciter component 22. The non-transitory computer-readable media merely indicates that the media is tangible and not a signal. The turbine controller 26, the starter controller 28, and the exciter controller 30 communicate with each other via a communication network 34. The communication network 34 may include an Ethernet-based network, such as the Unit Data Highway (UDH) provided by General Electric.
Generally, the turbine 12 may rotate a shaft in the generator 14, such that the generator 14 outputs a voltage. The voltage output of the generator 14 may then be synchronized with the voltage of the electrical grid 24 and provided to the electrical grid 24 via the switch 16. The exciter controller 30 monitors electrical properties of the grid 24. As such, the exciter controller 30 monitors the grid 24 for transient events such as a rise or fall in grid frequency, a rise or fall in active power or reactive power of the generator 14, and the like. The transient event may include changes to electrical properties such as voltage, current, power, power factor, and the like.
Prior to the occurrence of a transient event and during a transient event, the exciter controller 30 may continuously determine an amount of mechanical power that is present on a shaft of the generator 14. That is, the exciter controller 30 may determine the amount of mechanical power present on the shaft of the generator 14 based on electrical data such as a terminal voltage output by the generator 14, a line current output by the generator 14, a power factor of the generator 14, a frequency/slip value, a shaft inertia value, and the like. During the transient event, the exciter controller 30 determines the mechanical power present on the shaft of the generator 14 and sends the determined mechanical power to the turbine controller 26 via the communication network 34.
Upon receiving the mechanical power from the exciter controller 34, the turbine controller 26 adjusts the operations of the turbine 12 to provide stability between the electrical properties of the grid 24 in view of the transient event and the rotation of the turbine shaft. As such, when the transient event occurs on the grid 24, the turbine controller 26 may adjust the rotation of the turbine shaft or compensate for the discrepancy between the rotation of the turbine shaft and the electrical properties of the grid 24 more quickly as compared to simply reacting to the transient event without the determined mechanical power.
Adjusting the rotation of the turbine shaft or, more generally, adjusting the operation of the turbine 12 may include modulating an air and fuel ratio used by the turbine 12 to rotate the turbine shaft, operating the turbine 12 in different Dry Low NOx (DLN) modes, adjusting fuel splints in various nozzles that are used for combustion in the turbine 12, and the like. Generally, by receiving the mechanical power on the shaft of the generator 14 during the transient event, the turbine controller 26 may continue the operation of the turbine 12 without causing instability in the combustion system of the turbine 12 or inducing compressor operation issues due to the transient event. That is, the turbine 12 may continue operating during the transient event such that operations of the turbine-generator system 10 may continue.
With the foregoing in mind, FIG. 2 illustrates a flow chart of a method 50 for sending a calculated mechanical power of a shaft during a transient event to a turbine in accordance with an embodiment. Although the method 50 is described below as being performed by the exciter controller 30, it should be noted that the method 50 may be performed by any suitable processor. Moreover, although the following description of the method 50 is described in a particular order, it should be noted that the method 50 may be performed in any suitable order.
Referring now to FIG. 2, at block 52, the exciter controller 30 monitors certain electrical properties associated with the grid 24, the generator 14, or both. The electrical properties may include a rise or fall in grid frequency, a rise or fall in active power or reactive power of the generator 14, voltage output by the generator 14 or the grid 24, current output by the generator 14 or the grid 24, power output by the generator 14 or the grid 24, power factor of the generator 14 or the grid 24, and the like. These electrical properties may be monitored using sensors such as voltage sensors, current sensors, and the like. Additionally, the exciter controller 30 may simulate the electrical properties based on data received from the sensors.
At block 54, the exciter controller 30 determines whether a transient event is detected on the output of the generator 14 or the grid 24 based on the monitored electrical properties. In one embodiment, the exciter controller 30 may detect the presence of a transient event according to the procedure described in U.S. Patent Application No. 14/315,727 . Alternatively, the exciter controller 30 may monitor the electrical properties and determine that a transient event is present when the electrical properties change more than some threshold within a certain period of time.
If the exciter controller 30 does not detect a transient event, the exciter controller 30 may return to block 52 and continue to monitor the electrical properties of the generator 14 and the grid 24. If, however, the exciter controller 30 detects the transient event, the exciter controller 30 proceeds to block 56.
At block 56, the exciter controller 30 calculates the mechanical power on the shaft of the generator 14 during the transient event. In one embodiment, the exciter controller 30 may determine the mechanical power on the shaft of the generator 14 during the transient event according to the process flow diagram of FIG. 3. Generally, the process flow diagram of FIG. 3 may determine the mechanical power (Pm) present on the shaft of the generator 14 based on certain properties such as accelerating power (Pacc) of the rotor in the turbine 12, power output by the generator 14 (Pe), inertia (H) on the shaft, and the like. The accelerating power (Pacc) is determined according to Equation (1) provided below. The power output by the generator 14 (Pe) may be measured by excitation system via a sensor, potential transformer feedback, current transformer feedback, and the like. The inertia (H) may be determined using certain tests and physical properties of the shaft.
As shown in the process flow diagram of FIG. 3, the derivative of the accelerating power (Pacc) may be multiplied by two times the inertia (H). The accelerating power (Pacc) may be characterized according to Equation 1 below. $Pacc = \int \frac{Pacc}{H} dt = \int \frac{Pm - Pe}{H} dt$
As such, with the process flow diagram of FIG. 3 in mind, the mechanical power on the shaft of the generator 14 may be determined according to Equations (2) and (3) below. $Pm = \frac{d}{dt} Pacc \times 2 H + Pe$
$Pm = \frac{d}{dt} [\int \frac{Pm - Pe}{H} dt] \times 2 H + Pe$
Referring back to FIG. 3, after calculating the mechanical power on the shaft during the transient event as described above, the exciter controller 30 proceeds to block 58. At block 58, the exciter controller 30 sends the calculated mechanical power to the turbine controller 26 via the communication network 34. Upon receiving the calculated mechanical power, the turbine controller 26 updates a model based control program that is being executed to control the operations of the turbine 12 using the calculated mechanical power.
With the foregoing in mind, FIG. 4 illustrates a method 70 for adjusting the operations of the turbine 12 based on a calculated mechanical power. Generally, the method 70 is described as being performed by the turbine controller 26, but it should be noted that any suitable processor capable of controlling operations of the turbine 12 may perform the method 70.
Referring to FIG. 4, at block 70, the turbine controller 26 may determine whether a calculated mechanical power of the shaft in the generator 14 was received from the exciter controller 30. If the turbine controller 26 has not received the calculated mechanical power, the turbine controller 26 may return to block 72 and continue to monitor whether it receives the calculated mechanical power.
If the turbine controller 26 receives the calculated mechanical power, the turbine controller 26 proceeds to block 74 and adjusts the operations of the turbine 14 based on the calculated mechanical power. That is, the turbine controller 26 may use the calculated mechanical power to determine an air and fuel ratio used by the turbine 12 to rotate the turbine shaft to provide the calculated mechanical power on the shaft, a Dry Low NOx (DLN) mode to use to provide the calculated mechanical power on the shaft, a combination of fuel splits in various nozzles for combustion in the turbine 12 to provide the calculated mechanical power on the shaft, and the like. It should be noted that Dry Low NO_x (DLN) combustion systems may utilize fuel delivery systems that typically include multi-nozzle, premixed combustors. DLN combustor designs utilize lean premixed combustion to achieve low NO_x emissions without using diluents such as water or steam. Lean premixed combustion involves premixing the fuel and air upstream of the combustor flame zone and operation near the lean flammability limit of the fuel to keep peak flame temperatures and NO_x production low.
Technical effects of the embodiments in the present disclosure include improving stability and effectiveness of the turbine-generator system 10 in light of transient events. That is, the operations of the turbine-generator system 10 may continue to be functional by performing the method described herein after the occurrence of a transient event. As a result, the turbine-generator system 10 may operate continuously and prevent the loss of power from the turbine-generator 10.
This written description uses examples to disclose embodiments described herein, including the best mode, and also to enable any person skilled in the art to practice the embodiments described herein, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the embodiments described herein is defined by the claims, and may include other examples that occur to those skilled in the art.

Claims

A system (10), comprising:
a turbine (12) comprising a first controller (26) configured to control one or more operations of the turbine (12);

a generator (14) configured to couple to the turbine (12), wherein the generator (14) is configured to provide power to an electrical grid (24);

an exciter (22) configured to provide a direct current (DC) voltage and a DC current to a rotor of the generator (14), wherein the exciter (22) comprises a second controller (30) which is communicatively connected to the first controller (26) via a communication network (34) and is configured to:
monitor (52) a first set of electrical properties associated with the electrical grid (24);

determine (54) whether a transient event is present on the electrical grid (24) based on the first set of electrical properties;

determine (53) a mechanical power present on a shaft of the generator (14) based on a second set of electrical properties associated with the generator (14), the electrical grid (24), or both in response to the transient event being present, wherein the second set of electrical properties comprises an inertia on the shaft in the generator (14), an accelerating power associated with a rotor of the turbine (12), and a power output by the generator (14), and wherein the mechanical power comprises an indication of energy used to rotate the shaft; and

send (58) the determined mechanical power to the first controller (26) via the communication network (34);

wherein the first controller (26) is configured to use the mechanical power received from the second controller (30) to update a model based control program to be executed to control operations of the turbine (12) and to adjust the one or more operations of the turbine (12) to provide stability between the first set of electrical properties of the grid (24) in view of the transient event and the rotation of the shaft, based on the received mechanical power.
The system of claim 1, wherein the one or more operations comprise air and fuel ratio of the turbine, a Dry Low NOx (DLN) mode of the tubine (12), an operation of one or more nozzles used for combustion within the turbine (12), or any combination thereof.
The system of any preceding claim, wherein the first set of electrical properties comprise a frequency associated with the electrical grid (24), active power associated with the generator (14), reactive power associated with the generator (14), voltage associated with the electrical grid (24), current associated with the electrical grid (24), power associated with the electrical grid (24), a power factor associated with the electrical grid (24), or any combination thereof.
The system of any preceding claim, wherein the second set of electrical properties comprises an accelerating power associated with a second rotor in the turbine (12), inertia on the shaft in the generator (14), or any combination thereof.
The system of any preceding claim, wherein the second controller (30) is configured to determine (54) the mechanical power according to: $Pm = \frac{d}{dt} [\int \frac{Pm - Pe}{H} dt] \times 2 H + Pe$
wherein Pm is the mechanical power, H is inertia on the shaft, and Pe is a power output by the generator (14).
The system of any preceding claim, wherein the second controller (30) determines that the transient event is present on the electrical grid (24) when a frequency, voltage, current, power, or power factor associated with the electrical grid (24) increases or decreases more than a threshold.
A method for use in a system including a turbine (12) comprising a first controller (26) configured to control one or more operations of the turbine (12), a generator (14) configured to couple to the turbine (12), wherein the generator (14) is configured to provide power to an electrical grid (24), and an exciter (22) configured to provide a direct current (DC) voltage and a DC current to a rotor of the generator (14), wherein the exciter (22) comprises a second controller (30) which is communicatively connected to the first controller (26) via a communication network (34), the method comprising:
monitoring (52), by the second controller (30), a first set of electrical properties associated with the electrical grid (24);

determining (54), by the second controller (30), whether a transient event is present on the electrical grid (24) based on the first set of electrical properties;

determining (56), by the second controller (30), a mechanical power present on a shaft in the generator (14) based on a second set of electrical properties associated with the generator (14), the electrical grid (24), or both in response to the transient event being present, wherein the second set of electrical properties comprises an inertia on the shaft in the generator, an accelerating power associated with a rotor of the turbine (12), and a power output by the generator (14), and wherein the mechanical power comprises an indication of energy used to rotate the shaft; and

sending (58) the mechanical power from the second controller (30) to the first controller (26) via the communication network (34);

wherein the first controller (26) uses the mechanical power received from the second controller (30) to update a model based control program which is executed to control operations of the turbine (12) and adjusts one or more operations of the turbine (12) to provide stability between the first set of electrical properties of the grid (24) in view of the transient event and the rotation of the shaft, based on the received mechanical power.
The method of claim 7, wherein the one or more operations comprise air and fuel ratio of the turbine, a Dry Low NOx (DLN) mode of the tubine (12), an operation of one or more nozzles used for combustion within the turbine (12), or any combination thereof.
The method of claim 7 or claim 8, wherein the first set of electrical properties comprise a frequency associated with the electrical grid (24), active power associated with the generator (14), reactive power associated with the generator (14), voltage associated with the electrical grid (24), current associated with the electrical grid (24), power associated with the electrical grid (24), a power factor associated with the electrical grid (24), or any combination thereof.
The method of any of the preceding claims 7 to 9, wherein the second set of electrical properties comprises an accelerating power associated with a second rotor in the turbine (14), power output by the generator (14), inertia on the shaft in the generator (14), or any combination thereof.
The method of any of the preceding claims 7 to 10, wherein the mechanical power is determined (56) according to: $Pm = \frac{d}{dt} [\int \frac{Pm - Pe}{H} dt] \times 2 H + Pe$
wherein Pm is the mechanical power, H is inertia on the shaft, and Pe is a power output by the generator (14).
The method of any of the preceding claims 7 to 11, wherein the transient event is determined (54) to be present on the electrical grid (24) when a frequency, voltage, current, power, or power factor associated with the electrical grid (24) increases or decreases more than a threshold.
A non-transitory computer readable medium comprising computer-executable instructions configured to cause a processor to perform the method of any one of the claims 7-12.